Trait PlatformYield 

pub trait PlatformYield {
    // Required method
    fn yield_now();
}

Scheduler yield primitive.

Used inside socket_wait_event and similar “let another task make progress” points where the caller isn’t actually waiting for I/O readability — the background read task already owns that — it just needs to relinquish the CPU so the real waiter can run.

Prior to Phase 77.22 each backend hand-rolled its own 1-ms busy sleep (libc::usleep(1000), vTaskDelay(1), tx_thread_sleep(1), k_usleep(1000), select(.., 1 ms)) — all with slightly different units and no common home.

ISR-safety: on the hosted-RTOS backends (FreeRTOS / NuttX / Zephyr / ThreadX) the underlying primitives panic or error when invoked from an ISR. Don’t call yield_now() from an interrupt handler.

Bare-metal has no real yield: there’s nothing to yield to. The default bare-metal impl is core::hint::spin_loop() (a pure CPU hint: emits YIELD / PAUSE / WFE depending on the arch, safe everywhere). Board crates that have armed an IRQ source may opt in to deep idle (wfi) via a separate BoardIdle hook — not part of this trait because calling wfi without an IRQ source deadlocks.

Required Methods

fn yield_now()

Relinquish the CPU long enough for another task / thread to run.

Non-blocking in the sleep sense — returns as soon as the scheduler has had an opportunity to pick a different runnable.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors